Physics, 06.11.2019 07:31 janilaw1

Awarehouse worker uses a forklift to raise a crate of pickles on a platform to a height 2.75 m above the floor. the combined mass of the platform and the crate is 207 kg. if the power expended by the forklift is 1440 w, how long does it take to lift the crate?

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Answer from: sophx

the time that takes lift the crate is 3.878s

Explanation:

Hello!

Briefly, the concept of work consists in the amount of energy it takes for a body to travel a certain distance, this is calculated as the product of the force by the distance parallel to the direction of the force.

To solve this exercise you must execute 2 steps.

1. Find the work done by the crate, which has a weight force and a height, which is calculated using the following equation

w=mgh

W=work(J)

m=mass =207kg

g=gravity=9.81m/s^2

h=2.75m

solving

W=(207)(9.81)(2.75)=5584.34J

2. Now remember that the concept of power is the amount of work a body does in a certain amount of time, so you use the following equation

$P=\frac{W}{t}$

where

P=power(W)=1440W

W=work=5584.34J

t=time(s)

solving for time

$t=\frac{W}{P}$

$t=\frac{5584.34}{1440}=3.878s$

the time that takes lift the crate is 3.878s

Answer from: Quest

the independent variable, or the one that is intentionally manipulated is the speed.

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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Awarehouse worker uses a forklift to raise a crate of pickles on a platform to a height 2.75 m above...

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